Who's the sheriff in lab-diagnostics town?

To know that specialized, targeted drugs are pharma's current rallying cry, you didn't have to follow the news out of this month's big cancer meeting. But it's the latest example of how drugmakers are using knowledge of cancer's genetic drivers to develop new treatments.

The American Society for Clinical Oncology meeting also put a spotlight on the other half of targeted cancer treatment: the diagnostic tests that can identify the patients most likely to benefit from a drug. These high-tech tests aren't limited to those that are closely linked with a particular drug therapy, and neither are they limited to cancer treatment. New tests look at single genetic mutations targeted by the latest drugs, but they also assess the interplay of dozens of genetic variants to predict the success of treatment, for instance. Or look at genetic changes over time to catch drug resistance. Or gauge the likelihood that a patient will develop particular types of cardiovascular disease. Or pinpoint the best doses for some key drugs. And so on.

Last year, we looked at the market for targeted drugs and their companion diagnostics, focusing on the in-vitro diagnostic kits regulated by the FDA as devices. But that leaves out an entire universe of tests increasingly important to the practice of medicine: lab-developed tests.

LDTs, as they are called, are, just as their label indicates, developed by labs for their use, rather than for sale as diagnostic kits. Labs are certified via the Centers for Medicare and Medicaid Services under the Clinical Laboratory Improvement Amendments, or CLIA. Individual assays aren't subject to mandatory validation. And that's something the FDA has had its eye on for several years, as lab tests moved beyond the simple diagnostic to the ever-more-complex tests used to make serious--sometimes life-or-death--treatment decisions.

Not everyone wants the FDA to get involved in this field, of course. Many labs believe they're quite well regulated now, thank you. Other LDT advocates have a variety of other ideas for policing new tests. At least one payer has stepped up with its own validation program. And rules promised by FDA are still in the works. Meanwhile, in the uncertainty, some would-be test developers and their would-be venture-capital backers are sitting on the sidelines, looking for clarity. With pharma walking hand-in-hand with diagnostic tests into the future, the questions are important.

We take an in-depth look at these and other issues in the LDT business and the latest on lab-test oversight in Waiting for Guidelines: Will FDA Take the Reins of Lab-Developed Tests? Check it out here. And if you're interested in more about targeted drugs and diagnostic tests, see our previous e-book, Companion Diagnostics: The Future of Medicine. -- Tracy Staton